Exchange group calendar is a tool by opusflow that talks to your exchange server just like outlook does.
It can help you with a number of things:

# Collates everyone’s calendar items into one or more public group calendars.
# Users don’t have to do anything. No software to install for the users.
# Selective filtering per group calendar to display only items that matter or hide private/confidential items.
# Create different group calendars for absence, projects and groups of resources (rooms, cars,..) that display only relevant calendar items.
# Admin users (managers) can push items to users directly from the group calendar overview and users can not change or remove those.
# Admin users (managers) can modify items in the groupcalendar and the change will replicate back to the user who has the item in the personal calendar.
# Team members can push team items to the personal calendar of everyone in their team so these will also display on mobile calendar devices.
# Users can create new items for other users from their personal calendar or pda/phone calendar.
# Define one mandatory, company wide category list and category color schema so everyone uses the same colors and categories.
# Group Calendars are accessible from Outlook web access. (web browser)
# Runs on any computer or server that can connect to the (hosted/local) Exchange server. No need to install on the exchange server.
# EGC Software management can be done from any computer that can connect to the machine that runs the EGC software.
# Uses the same methods to talk to Exchange as Outlook, nothing needed on the server. Low server load even with high user counts.
# No left-overs when uninstalled. Registry is not used.
# Centrally schedule appointments and events for team members
# End the 'delegate permissions' problems. No permissions settings by users